Hydraulic torque converter

ABSTRACT

A hydraulic torque converter, particularly for use in a motor vehicle between the prime mover and the transmission of the power train, employs a combination of a bypass clutch with one or more torsional vibration dampers which brings about savings in space and/or in the number of parts. In addition, the torque converter can stand long periods of use and is less prone to wear, adverse influences of abruptly developing stresses and/or other undesirable influences than conventional torque converters. Furthermore, the improved torque converter employs or can employ a bypass clutch and/or one or more torsional vibration dampers simpler and less expensive than but superior to those in conventional torque converters.

BACKGROUND OF THE INVENTION

[0001] The invention relates to improvements in torque transmittingapparatus, and more particularly to improvements in hydraulic torqueconverters which can be utilized with advantage in the power trains ofmotor vehicles, e.g., between the rotary output element of the primemover (such as an internal combustion engine) and the input element(such as a shaft) of a change-speed transmission.

[0002] A conventional hydrokinetic torque converter in the power trainof a motor vehicle normally comprises a housing which shares the angularmovements of the output element (such as the crankshaft) of the engine,a pump which shares the angular movements of the housing, a turbinewhich can receive torque from the housing by way of a body of hydraulicfluid confined in the housing and being circulated by the vanes orblades of the pump, as well as an output member (e.g., a hub) which canreceive torque from the turbine to transmit torque to a driven membersuch as the input shaft of the change-speed transmission. The torqueconverter can further comprise a bypass clutch or lockup clutch(hereinafter called bypass clutch) which, when necessary or desired,transmits torque directly between the pump or housing and the turbine.Still further, such conventional torque converter can also comprise atleast one torsional vibration damper which operates in the power trainbetween the housing and the output member.

[0003] In many conventional torque converters of the above outlinedcharacter, a portion of the bypass clutch is fixedly secured to theinput of the torsional vibration damper. Reference may be had, forexample, to published German patent application Serial No. 199 63 236A1. The piston of the bypass clutch is or can be riveted to the input ofthe torsional vibration damper and such input comprises two annularflanges. During actuation (engagement or disengagement) of the bypassclutch, the piston of the bypass clutch is caused to move axially and tothus frictionally engage or become disengaged from the housing of thetorque converter. Such axial movement of the piston entails a movementof the output of the torsional vibration damper because the output isprovided with gear teeth mating with complementary gear teeth on the hubof the torque converter.

[0004] It can happen that the mating gear teeth generate pronouncedfriction or that they jam. In fact, the tension between the input of thetorsional vibration damper and the piston of the bypass clutch, and/ornon-uniform engagement of the piston of the bypass clutch with thefriction surface of the housing of the torque converter, can cause thedevelopment of excessive stresses, a cracking of cooperating parts andfatigue-induced breaks. Such undesirable phenomena are particularlylikely to develop in the parts which are riveted to each other. Stillfurther, excessive tension between the piston of the bypass clutch andthe input of the torsional vibration damper is likely to develop whenthe piston is caused to frictionally engage the housing with attendantdeformation (particularly in the axial direction of the bypass clutch)when the pressure of hydraulic fluid in the cylinder chamber for thepiston increases, i.e., when the piston is called upon to transmittorque from the housing to the output of the torque converter byestablishing a direct power transmitting path from the output element ofthe prime mover, through the housing of the torque converter and to theoutput of the latter, i.e., by bypassing the pump and the turbine of thetorque converter.

[0005] The torsional vibration damper comprises coil springs or othersuitable resilient elements which act in the circumferential directionof the input and output when the input turns relative to the outputand/or vice versa. When the RPM of the torsional vibration damper isvery high, the springs are held against radially outward movement underthe action of centrifugal force. The means for preventing such radiallyoutward movements of the springs are costly as well as bulky becausethey take up room as considered axially as well as radially of thedamper. In order to achieve most satisfactory friction within the entireRPM range of the springs, it is necessary to establish an optimumrelationship between the parts which can or should turn relative to eachother, especially between the coil springs on the one hand and the inputand/or output of the torsional vibration damper on the other hand.

[0006] It is often advisable to connect the torque converter to anaxially elastic disc or wall which is attached to and receives torquefrom the output shaft of the prime mover (such as the crankshaft of theengine) in the power plant of a motor vehicle. The connection isnormally established by resorting to threaded fasteners having shanksmating with internal threads provided in one of the torque converter andthe disc. This normally involves individual application and tighteningof each of a plurality of threaded fasteners. Such tightening is carriedout by resorting to a suitable tool which can reach the fastenersthrough one or more access openings provided in the housing or bell ofthe change-speed transmission of the power train. The torque convertermust be caused to turn, at least at intervals, in order to afford accessto the fasteners. Such modes of affixing the torque converter to thetorsional vibration damper and of mounting the damper in the torqueconverter are time-consuming and necessitate the hiring of highlyskilled artisans. The situation is complicated because the installationof a torque converter in the power train of a vehicle also invariablynecessitates the hiring of highly skilled artisans who are capable ofcarrying out the above outlined undertakings in addition to centering ofcooperating moving (rotary) parts relative to the adjacent part orparts.

OBJECTS OF THE INVENTION

[0007] An object of the instant invention is to provide a hydraulictorque converter which is more reliable than heretofore known torqueconverters and whose useful life is much longer than those of theaforediscussed and other conventional apparatus of such character.

[0008] Another object of the invention is to provide a torque converterwhich can be assembled and installed in the power train of a motorvehicle or the like in a manner much simpler than conventional torqueconverters.

[0009] A further object of the present invention is to provide a torqueconverter which is constructed and assembled with a view to reduce theeffects of fatigue upon its useful life and/or upon the reliability ofits operation and which is more likely to withstand the effects ofunanticipated stresses, hard-to-detect cracks and/or breaks as well asweakening of joints, connections and wear-induced problems thanconventional torque converters.

[0010] An additional object of this invention is to provide a novel andimproved method of assembling a torque converter and of installing suchapparatus—in partly or fully assembled condition—in the power train of amotor vehicle.

[0011] Still another object of the invention is to provide one or morenovel and improved torsional vibration dampers for use in theaforediscussed novel hydraulic torque converter.

[0012] A further object of the invention is to provide a novel andimproved combination of a bypass clutch and one or more torsionalvibration dampers for use in a hydraulic torque converter.

[0013] Another object of this invention is to provide a torque converterwhich embodies a bypass clutch and wherein the generation and/orapplication or utilization of friction and/or damping can be initiatedand controlled in a manner more reliable and more predictable than inconventional torque converters.

[0014] An additional object of the invention is to provide a torqueconverter whose operation is more reliable and more predictable withinthe entire RPM range of the rotary output element or elements of theprime mover, such as the camshaft or the crankshaft of the internalcombustion engine in the power train of a motor vehicle, than theoperation of conventional torque converters.

[0015] Still another object of the invention is to provide a novel andimproved method of operatively connecting the improved torque converterwith a shaft, disc or another rotary output element of a prime mover.

[0016] A further object of our invention is to provide a torqueconverter wherein one or more rotary and/or otherwise movable parts ofthe bypass clutch, of one or more torsional vibration dampers and/or oneor more other components can be centered in a manner simpler, morereliable and less time-consuming than that required for analogousmanipulation(s) of components in conventional torque converters.

[0017] Another object of the invention is to simplify the assembly ofthe torque converter with a prime mover and/or with a driven unit (suchas a variable-speed transmission) in the power train of a motor vehicle.

[0018] An additional object of the invention is to provide a torqueconverter which is constructed and assembled in such a way that itsspace requirements in a motor vehicle (such as between the engine andthe transmission) are much less than in heretofore known power trains.

[0019] Still another object of the invention is to provide a power trainwhich can be utilized in any one of a large number of different powertrains to meet one or more specific or broad requirements pertaining tosavings in space, material and/or number of parts, to reliability and/oruseful life, to the possibility to occupy space which is avaiable underthe hood of or elsewhere in a motor vehicle and/or to meet two or moreof the above-enumerated and/or other prerequisites.

[0020] A further object of the instant invention is to provide a powertrain, particularly for use in a motor vehicle, which embodies a torqueconverter exhibiting at least some of the above-enumerated features andattributes.

SUMMARY OF THE INVENTION

[0021] One feature of the present invention resides in the provision ofa hydraulic torque converter which comprises a housing arranged torotate about a predetermined axis, to confine a supply of a suitablehydraulic fluid and to receive torque from an output element of a primemover (e.g., from the crankshaft of an internal combustion engine in thepower train of a motor vehicle). The improved torque converter furthercomprises a pump which is disposed in and is arranged to rotate with thehousing about the predetermined axis, and an annular turbine which iscoaxial with the pump, which is disposed in the housing and which isarranged to receive torque from the fluid in the housing in response torotation of the pump. The improved torque converter also comprises arotary input element (e.g., the input shaft of a change-speedtransmission) which is coaxial with the housing, a rotary output member(such as a hub) which is arranged to transmit torque between the inputelement and at least one of the pump, turbine and housing, a bypassclutch which is engageable to transmit force between the pump and theturbine during predetermined stages of operation of the torqueconverter, and at least one torsional vibration damper in a power flowbetween the housing and the output member. The damper comprises aninput, an output which is coaxial with the housing and with the inputand is rotatable relative to the input, and energy storing meansarranged to oppose rotation of the input and the output relative to eachother.

[0022] The improved torque converter can further comprise a statorwhich, if used, is installed between the pump and the turbine.

[0023] The input element can include or constitute or form part of ashaft of an automatic change-speed transmission.

[0024] The bypass clutch can include a substantially disc-shaped memberand the torque converter can further comprise means for resilientlyconnecting the disc-shaped member to the input of the damper withfreedom of movement in the direction of the axis of the housing. Thesubstantially disc-shaped member can include or constitute a piston ofthe bypass clutch, and such torque converter can further comprise aforce-locking connection between the piston and the housing; suchconnection can include friction surfaces which contact each other in theengaged condition of the bypass clutch.

[0025] The aforementioned member (piston) of the bypass clutch can beconnected with the input or with the output of the damper at a pluralityof points which are spaced apart from each other in the circumferentialdirection of the turbine. The input or the output of the damper and/orthe member (piston) of the bypass clutch can be provided with stiffnessreducing means disposed at least partially radially inwardly of theaforementioned array of connection points, namely with means forreducing the stiffness of the input, output or piston in the directionof the predetermined axis.

[0026] The stiffness reducing means can include an annular array ofrecesses in the input, output or piston, and each such recess can beadjacent one of the aforementioned plurality of points. For example,each recess can include an arcuate slit which partially surrounds one ofthe points. The width of one end portion of each slit can exceed thewidth of the other end portion and/or the width of an intermediateportion of the respective slit. One end portion of each recess or slitin the input, output or piston can extend radially outwardly beyond atleast one of the aforementioned points.

[0027] If the recesses are slits provided in the input of the torsionalvibration damper, such slits can be provided in the radially outermostportion of the input and can have open ends at the periphery of theinput.

[0028] An enlarged end of each slit can be spaced apart from the axis ofthe housing the same distance as the aforementioned points.

[0029] The slits, recesses or other suitable stiffness reducing meanscan be provided in the input or output of the damper and/or in thepiston of the bypass clutch during a first stage of assembly of thedamper with the housing and the output member, and the input can undergoa shaping treatment (such as the imparting of the final shape) during asecond stage which follows the first stage of assembly of the damperwith the housing and with the output member.

[0030] The damper can be installed in a power flow between the bypassclutch and the output member or in a power flow between the turbine andthe output member.

[0031] The input of the damper can include at least two walls or panels,and such torque converter can further comprise means (such as rivets)for connecting at least one wall of the input with a member (such as apiston) of the bypass clutch.

[0032] A portion of the bypass clutch can be placed next to a portion ofthe torsional vibration damper, and such torque converter can furthercomprise an annular array of fasteners (such as rivets) which spacedlysurround the axis of the housing and connect the two portions to eachother. Such torque converter can further comprise means (such as theaforementioned slots) for reducing the stiffness of at least one of theinterconnected portions in the axial direction of the housing. Theslots, recesses or analogous stiffness reducing means are or can beadjacent the fasteners. Each such recess or slot can be open as seenradially outwardly away from the axis of the housing and closed radiallyinwardly of neighboring fasteners. The recesses can alternate with thefasteners, and the widths of at least some of the recesses—as seen inthe circumferential direction of the portions of the damper and bypassclutch—can increase in a direction toward the axis of the housing.

[0033] It is also possible to provide the input or the output of thedamper and/or the piston of the bypass clutch with recesses havingclosed radially inner end portions nearest to the axis of the housingand bounded by at least substantially circular surfaces of the input,output and/or piston; each such recess can resemble a keyhole.

[0034] The widths of at least some of the recesses—as seen in thecircumferential direction of the housing can decrease in a directiontoward the axis of the housing. For example, such recesses can bebounded by an undulate peripheral surface of the input, output and/orpiston.

[0035] A portion (such as the aforementioned piston) of the bypassclutch can be connected to a portion (such as the input) of the damperby suitable springs with limited freedom of movement in the direction ofthe axis of the housing of the improved torque converter. The springscan include an annuar array of leaf springs which spacedly surround theaxis of the housing. Such torque converter can further comprise meansfor non-rotatably connecting the input of the damper with the turbine.The piston of the bypass clutch and the housing include annular portionswhich frictionally engage each other in the engaged condition of thebypass clutch, and the aforementioned leaf springs can connect the inputof the damper with a radially outermost part of the aforementionedportion (piston) of the bypass clutch.

[0036] The energy storing means of the at least one damper can includean annulus of coil springs and means for limiting the movability of suchsprings at least radially of the axis of the housing. The means forlimiting can include a ring which is surrounded by the convolutions ofthe coil springs with limited freedom of movement of the springs andring relative to each other radially of the axis of the housing. Suchtorque converter can further comprise means for connecting the ring tothe damper, namely to the input or the output of the damper. The ringcan be made of any suitable material, especially a metallic or a plasticmaterial.

[0037] The means for limiting can include a preshaped annular member andthe convolutions of the coil springs forming part of the damper spacedlysurround the preshaped annular member. The end portions of the lattercan be affixed to each other by bonding (such as welding), by hooking(i.e., by resorting to one or more hooks at one end of the annularmember and to one or more eyelets for such hook or hooks at the otherend of the annular member) or by nesting (e.g., by fitting a male memberat one end into a complementary female member at the other end of theannular member).

[0038] The input and/or the output of the damper can include means forlocating the annular member relative to the input and the output in atleast one of the directions including radially of the axis of thehousing and in the direction of such axis. The locating means caninclude an annular array of discrete projections provided on the inputand/or on the output of the damper. The projections can further serve asa means for tensioning the annular member. Each such projection caninclude a deformed portion of the input and/or the output of the damper.

[0039] The ratio of the diameter d of the wire of the ring to the innerdiameters D of convolutions of the coil springs is or can be determinedby the relation-ship 0.8*D>d>0.2*D, preferably by the relationship0.6*D>d>0.3*D.

[0040] The springs of the energy storing means can be received inrecesses provided therefor in the input of the damper, and such inputcan be further provided with at least substantially radial armsalternating with the recesses, as seen in the circumferential directionof the damper. The output of such damper can include entraining portionswhich cooperate with the arms to stress the springs in response torotation of the input relative to the output and/or vice versa.

[0041] The arms and/or the entraining means can be provided withsurfaces which at least substantially conform to the surfaces ofadjacent portions of the springs forming part of the energy storingmeans.

[0042] One or more springs of the energy storing means can be installedin prestressed condition, i.e., such springs are caused by the adjacentarms to store energy even in neutral angular positions of the input andoutput of the damper relative to each other. Alternatively or inaddition to the just mentioned feature, the springs can be maintained inprestressed condition by the entraining portion of the output of thedamper. The recesses of the input of the damper can be bounded bysurfaces making right angles with each other.

[0043] Another feature of the present invention resides in the provisionof a hydraulic torque converter which comprises a housing including amass and being arranged to rotate about a predetermined axis, to confinea supply of hydraulic fluid and to receive torque from an output elementof a prime mover. The improved torque converter further comprises a pumpwhich is disposed in and is arranged to rotate with the housing aboutthe latter's axis, an annular turbine which is coaxial with the pump,which is disposed in the housing and which is arranged to receive torquefrom the fluid in the housing in response to rotation of the pump, arotary input element which is coaxial with the housing, a rotary outputmember which is arranged to transmit torque between the input elementand the pump, housing and/or turbine, and a bypass clutch which isengageable to transmit force between the pump and the turbine duringpredetermined stages of operation of the torque converter. The latterfurther comprises at least one torsional vibration damper including aninput, an output coaxial with the housing and with the input androtatable relative to the input, energy storing means arranged to opposerotation of the input and output relative to each other, and a torquetransmitting member between the output element and the input. Stillfurther, the torque converter comprises an annular array of retainingmembers provided on the mass and received in openings provided thereforin the torque transmitting member, and means for holding the retainingmembers in the respective openings.

[0044] The retaining members can include pins having axes at leastsubstantially parallel to the axis of the housing and including endportions which extend or can extend through and beyond the respectiveopenings; the holding means can engage such end portions of the pins.Such holding means can extend at least substantially circumferentiallyof the torque transmitting member.

[0045] In accordance with one presently preferred embodiment, theholding means includes a ring-shaped support and discrete holdingmembers provided on the ring-shaped support and each engaging one of theretaining members.

[0046] The torque transmitting member can be disposed between the primemover and the mass of the housing, as seen in the axial direction of thehousing.

[0047] At least one of the retaining members can have an at leastsubstantially conical shape and the corresponding opening has acomplementary shape to snugly receive the conical retaining member.

[0048] The openings are or can be provided in a reinforced portion ofthe torque transmitting member; the latter can include a substantiallydisc-shaped body having a folded over radially outermost part whichconstitutes the reinforced portion of the torque transmitting member.

[0049] The mass of the housing can constitute an annular body, and theholding means can include forks each of which has prongs extending atleast substantially circumferentially of the annular mass and engagingfree end portions of the respective retaining members. The prongs can bereceived in grooves provided therefor in the free end portions of therespective retaining members. It is advisable to ensure that the forksare maintained in frictional engagement with the torque transmittingmember and with the respective retaining members.

[0050] As already mentioned hereinbefore, the holding means can includea discrete holding member for each of the retaining members and aring-shaped support for the holding members. Such torque converter canfurther comprise means for securing the ring-shaped support to thetorque transmitting member against accidental separation from thelatter.

[0051] The retaining members can include or constitute forks whichextend circumferentially of the ring-shaped support. Each fork engagesone of the retaining members and is separable from the respectiveretaining member in response to rotation of the ring-shaped supportrelative to the mass and/or vice versa. The forks cooperate with theretaining members to hold the ring-shaped support against movementrelative to the mass in the axial direction of the housing.

[0052] The torque converter can further comprise means for preventingundesired rotation of the ring-shaped support relative to the mass whenthe retaining members are held in the respective openings. The rotationpreventing means can comprise at least one snap fastener; such snapfastener can include a detent which is provided on the holder or on thetorque transmitting member of the damper and an opening for the detentin the torque transmitting member or in the holder.

[0053] The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theimproved torque converter itself, however, both as to its constructionand the modes of assembling, installing and utilizing the same, togetherwith numerous additional important and advantageous features andattributes thereof, will be best understood upon perusal of thefollowing detailed description of certain presently preferred specificembodiments with reference to the acccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

[0054]FIG. 1 is an axial sectional view of a hydraulic torque converterwhich embodies one form of the present invention and is installedbetween the rotary output shaft of an engine and the input element of achange-speed transmission in the power train of a motor vehicle;

[0055]FIG. 2 is an elevational view of the input and of the energystoring means of the torsional vibration damper in the torque converteras seen from the left-hand side of FIG. 1;

[0056]FIG. 3 is an enlarged view of a detail within the phantom-linecircle III shown in FIG. 1;

[0057]FIG. 4 is a fragmentary elevational view of the input in amodified torsional vibration damper and of an assembly which connectsthe input to a disc borne by the output shaft of the engine;

[0058]FIG. 5 is a sectional view substantially as seen in the directionof arrows from the arcuate phantom line V-V in FIG. 4;

[0059]FIG. 6 is a substantially axial sectional view as seen in thedirection of arrows from the line VI-VI in FIG. 7 and shows a modifiedtorsional vibration damper which can be utilized in the hydraulic torqueconverter of the present invention;

[0060]FIG. 7 is a fragmentary elevational view of the input and of theenergy storing means in the damper, as seen from the left-hand side ofFIG. 6, and further shows the means for fastening the damper to thepiston of the bypass clutch forming part of a torque converter embodyingthe damper shown in FIG. 6;

[0061]FIG. 8 is a view similar to that of FIG. 7 but shows a portion ofa modified input;

[0062]FIG. 9 is a view similar to that illustrated in FIG. 7 but showingcertain constituents of an additional torsional vibration damper and ofthe means for affixing it to the piston of the bypass clutch;

[0063]FIG. 10 is a fragmentary elevational view of the input in anadditional torsional vibration damper and of an array of fasteners whichsecure the input to the piston of a bypass clutch, e.g., a clutch of thetype shown in FIG. 1;

[0064]FIG. 11 is a fragmentary elevational view of an input forming partof still another torsional vibration damper and constituting amodification of the input shown in FIG. 10;

[0065]FIG. 12 is a fragmentary axial sectional view of a hydraulictorque converter constituting a further modification of the torqueconverter shown in FIG. 1 including a different non-rotatable butaxially yieldable connection between the piston of the bypass clutch andthe input of the torsional vibration damper;

[0066]FIG. 13 is an enlarged view of a detail as seen in the directionof arrow XIII which is shown in FIG. 12;

[0067]FIG. 14 is an enlarged view of a detail as seen in the directionof arrow XIV which is shown in FIG. 12; and

[0068]FIG. 15 is a fragmentary axial sectional view of a hydraulictorque converter constituting a further modification of the torqueconverter which is illustrated in FIG. 1, and more specifically of adifferent connection between the bypass clutch and the torsionalvibration damper.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0069] The hydraulic torque converter 1 which is shown in FIG. 1comprises a housing 13 which is affixed to the output element 2 of aprime mover, not shown. The output element 2 can constitute thecrankshaft of an internal combustion engine in the power train of amotor vehicle; such power train further includes a rotary output element3 of a change-speed transmission (not shown) which can drive the wheelsor certain wheels of the motor vehicle by way of a differential in amanner well known in the art. The torque converter 1 is a fluid-operatedclutch which can be utilized in lieu of a dry friction clutch touncouple the engine in order to stop the motor vehicle in gear or tocouple the engine for acceleration. Reference may be had, for example,to pages 691-693 of “Modern Automotive Technology” by James E. Duffy(1994 Edition published by The Goodheart-Willcox Company, Inc., TinleyPark, Ill.). As concerns the operation of a power train which employs afriction clutch, in lieu of a torque converter, reference may be had,for example, to commonly owned U.S. Pat. No. 4,901,596 granted Feb. 20,1990 to Reik et al. for “ASSEMBLY FOR TAKING UP AND COMPENSATING FORTORQUE-INDUCED SHOCKS”.

[0070] The input element 3 preferably constitutes the input shaft of anautomatic or automated change-speed transmission. The housing 13comprises coaxial shells 4 and 5 which are sealingly secured (such aswelded) to each other. It is also possible to connect the shells 4, 5 toeach other by resorting to threaded fasteners, to caulking, to a bayonetlock, to a snap-in connection or the like. It is advisable to employ oneor more washers and/or other metallic, plastic or other elastic sealingelements and/or to resort to a press fit in order to ensure adequatesealing of the interior of the housing 13 from the surroundingatmosphere.

[0071] The means for non-rotatablv securing the shell 4 of the housing13 to the output shaft 2 of the prime mover comprises an axiallyyieldable elastic torque-transmitting disc 6 having a radially innerportion affixed to the shaft 2 by an annular array of threaded fasteners2 a (two can be seen in FIG. 1). These fasteners further serve as ameans for ensuring that the axis XX of the housing 13 coincides with theaxis of the output shaft 2 as well as with the common axis of rotarycomponents of the torque converter 1.

[0072] The annular radially outermost portion 6 a of the torquetransmitting disc 6 is reinforced in that it is folded over itself,e.g., in a suitable cold forming machine. This outermost portion 6 a isaffixed to a ring-shaped portion or flywheel or mass 8 of the housing 13in a novel manner, namely by a fastener assembly 10. The lattercomprises an annular array of preferably equidistant conical retainingmembers or projections 7 in the form of short pins borne by the mass 8and snugly received in complementary conical openings 6 b provided inthe reinforced portion 6 a of the disc 6. The axes of the projections orpins 7 are parallel to the axis X-X of the housing 13, and these pinsextend in a direction from the shell 4 of the housing 13 toward theengine including the output shaft 2. The mass 8 is centered on and iswelded or otherwise affixed to the shell 4; this mass is acircumferentially complete body but it can be replaced with a set ofdiscrete segments each of which can carry one or more abutments or pins7.

[0073] The radially outermost portion of the shell 4 is recessed in adirection axially of and away from the disc 6 in order to provide roomfor the mass 8, i.e., to thus contribute to a reduction of axial lengthof the housing 13 and hence of the entire torque converter 1. Thearrangement can be such that the left-hand side of the mass 8 need noteven extend to the plane of the leftmost portion of the shell 4. Theillustrated mass 8 is at least substantially coplanar with and spacedlysurrounds the heads of the threaded fasteners 2 a. This is made possiblebecause the central portion of the shell 4 is also recessed in adirection away from the torque transmitting member or disc 6.

[0074] Each projection 7 has a stud-shaped extension 7 a which isrecessed into the mass 8; for example, each stud 7 a can be providedwith an external thread mating with a complementary internal thread inthe respective tapped bore or hole of the mass 8. Alternatively, and ifthe projections 7 are to serve solely as a means for centering (or as ameans for assisting the centering) of the mass 8 on the disc 6, theseprojections can be welded or otherwise more or less permanently affixedto the mass.

[0075] The means for holding the torque converter against axial movementrelative to the disc 6 includes a ring-shaped support here shown as abayonet lock 9 having openings 9 a for entry of tips (free end portions)of the projections 7 in one (non-locking) angular position of thebayonet lock. The latter is thereupon turned so that its fork-shaped orstud-shaped holding members 9 c enter complementary openings 7 b of theprojections 7. Blocking devices 9 d in the form of snap fasteners on thebayonet lock 9 then enter complementary openings 6 c by snap action. Inorder to prevent accidental separation of the bayonet lock 9 from thedisc 6, the peripheral portion of the member 9 is provided with anannular array of axially extending resilient tongues 9 c which engageadjacent portions of the peripheral surface of the disc 6.

[0076] It is within the purview of the present invention to employ astarter gear (not shown) which is affixed to the disc 6 or to the mass8, or which forms part of the member 6 or 8. Furthermore, the mass 8and/or the disc 6 can be provided with a customary arrangement ofindicia (e.g., in the form of notches) which can be monitored by meansserving to control the operation of the combustion engine including theshaft 2. Alternatively, such indicia can be provided on a discrete part(not shown) which is affixed to the disc 6 or to the mass 8.

[0077] The fastener assembly 10 is shown in greater detail in FIGS. 4and 5. As already mentioned hereinbefore, this assembly serves toseparably connect the torque transmitting disc 6 with the torqueconverter 1. FIG. 4 is a fragmentary front elevational view of thefastening assembly 10 as seen in the direction of the arrow IV in FIG.1, and FIG. 5 is a sectional view as seen in the direction of arrowsfrom the arcuate line V-V shown in FIG. 4. As can be seen in FIG. 4, thebayonet lock 9 is affixed to the axially elastic torque transmittingdisc 6 (e.g., a body made of a suitable metallic sheet material). Thetensioning or holding forks 9 c (only one shown in each of FIGS. 4 and5) extend circumferentially of the bayonet lock 9; for example, thisbayonet lock can be provided with at least three forks 9 c with pairs ofprongs 9 c′, 9 c″ bent out of the plane of the major part or body of thebayonet lock so that the prongs are spaced apart from and parallel toone side of the major part. The prongs 9 c′, 9 c″ flank the tip 7 c ofthe respective projection 7 and extend into the respective opening 7 b.

[0078]FIG. 4 shows one of the forks 9 c of the bayonet lock 9 in fullengagement with the tip 7 c of the respective projection 7, i.e., thetip 7 c prevents any further angular movement of the bayonet lockrelative to the torque transmitting disc 6. The projection 7 is urgedinto the respective complementary opening 6 b of the disc 6 so that theperipheral surface of this projection is in frictional engagement withthe surface bounding the opening. A detent including a snap fastenertongue 9 d extends into the opening 6 c of the disc 6 so that the parts6 and 8 are releasably locked against angular movement relative to eachother. It will be noted that proper assembly of the disc 6 with thehousing 13 merely necessitates a slight turning of the parts 6, 8relative to each other as soon as the projections 7 are received in thecomplementary openings 6 b; this is much simpler and less time-consumingthan the conventional procedures which normally involve the utilizationof a set of screws or bolts and nuts which are individually applied tosecure the disc 6 or an equivalent thereof to the housing of the torqueconverter.

[0079] The mode of utilizing the fastening assembly 10 is as follows:The torque converter 1 is assumed to be properly assembled with thechange-speed transmission including the input shaft 3 In order to mountthe transmission on the output shaft 2 of the engine, the projections 7are inserted into their respective complementary openings 6 b. Anauxiliary tool 11 (shown in FIG. 4 by phantom lines and preferablyconstituting a suitably configurated piece of metallic sheet material)is employed to thereupon turn the bayonet lock 9 relative to the disc 6until the extension 9 d terminates such turning in that it enters theopening 6 c. A similar tool can be employed to initiate a disengagementof the disc 6 from the projections 7 of the mass 8 and housing 13; suchtool is utilized to lift the snap fastener 9 d out of the opening 6 cand to thus release the housing 13 for angular movement relative to thedisc 6, i.e., the bayonet lock 9 is disengaged from the tips of theprojections 7.

[0080] An advantage of the just described undertakings involving aconnection of the housing 13 (i.e., of the torque converter 1) to thedisc 6 (i.e., to the output shaft 2) and a disengagement of the housingfrom the disc is that such procedures can be carried out withoutnecessitating the provision of any additional space in the direction ofthe axis X-X. Another advantage of such mounting of the housing 13 onthe disc 6 and shaft 2 is that rotation of the bayonet lock 9 relativeto the reinforced radially outermost portion 6 a of disc 6 results insimultaneous locking of all projections 7 in the respective openings 6 bof the disc without necessitating any repeated turning of the shaft 2.This is in contrast with conventional procedures which involve theutilization of several screws, bolts and nuts or like threadedfasteners. Thus, in order to remove all of the threaded fasteners, it isnecessary to repeatedly index a conventional torque converter in orderto move successive threaded fasteners to a position in which they can bereached by a wrench or another suitable tool.

[0081] A single turning of the bayonet lock 9 relative to the disc 6 andhousing 13 releases all of the fasteners 7 for withdrawal from therespective openings 6 b of the disc 6, or such single turning effects aretention of all fasteners in their respective openings; this featurealone contributes to substantial savings in time during mounting of thetorque converter 1 on or during its separation from the disc 6 and shaft2. Though it is possible to remove all of the threaded fasteners of aconventional connection between the torque converter and the outputshaft of an engine without repeatedly turning the shaft and/or thehousing of the torque converter, this is possible only if the fullyinstalled conventionally mounted torque converter provides access toseveral nuts or screws without any changes in its angular position; thiscan be achieved only by resorting to a pronounced increase of thecombined axial length of the engine and the torque converter.

[0082] The bayonet lock 9 can be made of a metallic or plastic sheetmaterial, e.g., of a plastic material which is reinforcd with carbonfilaments and/or with other suitable reinforcing or stabilizingmaterials.

[0083] As can be seen in FIG. 5, the forks 9 c (only one shown) of thebayonet lock 9 can also serve to accurately center the housing 13 of thetorque converter 1 (such housing is rigid with the fasteners 7 and themass 8) on the disc 6 in that the prongs 9 c′, 9 c″ (see FIG. 4) of theforks can engage the neck of the respective fastener without any playwhen the detent 9 d snaps into the adjacent recess 6 c of the disc 6. Asalso shown in FIG. 5, the extension 7 a of the fastener 7 shown thereinis received in the mass 8 without play. The bayonet lock 9 cooperateswith the fastener 7 to properly center the mass 8 relative to the disc6.

[0084] It is clear that the fastener assembly 10 or an equivalentthereof can be utilized with advantage in many conventional power trainsto non-rotatably but releasably secure two or more parts to each other.For example, such assembly can be utilized in many conventional powertrains to secure a torque converter or a friction clutch to the outputelement of an engine or another prime mover; such conventional powertrain need not embody any other features of the torque converter whichis disclosed in the present application. Furthermore, the improvedfastener assembly 10 can be utilized to mount and center a frictionclutch on the input shaft of a change-speed transmission in a powertrain wherein the clutch is employed in lieu of a torque converter.Still further, the disc 6 can be replaced with a rigid disc which doesnot permit any or any appreciable axial movements of the housing 13relative to the output shaft 2. The illustrated axially yieldableresilient disc 6 is preferred in many instances because it is capable ofdamping at least some stray movements of the shaft 2 and housing 13relative to each other in the direction of the axis X-X as well as atleast some wobbling movements relative to such axis.

[0085] The torque converter 1 further comprises a pump or impeller 12which is coaxial with and shares the angular movements of the shell 5, aturbine 14 which is disposed in and is rotatable with as well asrelative to the housing 13, and preferably also a stator 16 which isinstalled between the pump 12 and the turbine 14 (as seen in thedirection of the axis X-X). The turbine 14 is rotated by the body of oilor other suitable hydraulic fluid in the housing 13 when the latterrotates with the pump 12 in response to rotation of the output shaft 2.The turbine 14 is non-rotatably connected with a rotary output member 15(hereinafter also called hub) which is non-rotatably connected to theinput element 3 by an internal gear 3 a.

[0086] The stator 16 can influence the transmitted torque and is mountedon a freewheel 16 a which surrounds the input shaft 3 of thetransmission. An important function of the stator 16 is to improve thecirculation of fluid in the housing 13. FIG. 1 shows that the stator 16is flanked by two distancing members 16 b, 16 c; the member 16 b ismounted on a suitable bearing 16 d (e.g., a friction bearing which isadjacent and can rotate relative to the radially innermost portion ofthe shell 5), and the member 16 c is adjacent an annular arrangement oflobes 16 e at the right-hand axial end of the hub 15. This hub has anaxial extension 15 a separated from the radially innermost portion ofthe shell 4 by a friction bearing 15 d.

[0087] The torque converter 1 further comprises a bypass clutch 17 whichcan be engaged to transmit torque directly between the shell 4 of thehousing 13 (i.e., directly from the output shaft 2) and the hub oroutput member 15. To this end, the bypass clutch 17 employs a member 19which acts as a piston in that it can be moved axially of the housing 13in order to place its annular friction surface 19 a into or away fromengagement with the confronting annular friction surface 4 a of theshell 4. A friction lining 20 can be affixed to the radially outermostportion of the piston 19 or to the shell 4 to define the frictionsurface 19 a or 4 a and to constitute or establish a force-lockingconnection between the piston 19 and the housing 13.

[0088] A torsional vibration damper 18 is installed in the power flowbetween the housing 13 and the hub 15 downstream of the bypass clutch17. The piston 19 of the clutch 17 is movable axially of the housing 13along the axial extension 15 a of the hub 15 into and away from abutmentwith a radially extending axial stop 15 b.

[0089] The friction lining 20 is optional; it can be utilized in orderto enhance the friction coefficient of the bypass clutch 17 and can beglued, riveted or otherwise affixed to the piston 19 or to the shell 4of the housing 13. It is also possible to employ two friction linings,one on the piston and the other on the shell 4. That side or surface ofthe friction lining 20 which constitutes the friction surface 4 a or 19a can be profiled (such as ribbed) to promote the cooling of the bypassclutch 17 in actual use. The profiling can be such that it allows for acontrolled flow of coolant between two chambers 21 and 22; such coolantis or can be the hydraulic fluid which causes the turbine 14 to rotatein response to rotation of the pump 12 during certain stages ofoperation of the torque converter 1. Cooling of the bypass clutch 17 isparticularly important when the clutch operates with slip, i.e., whenthe surfaces 4 a, 19 a bear against and slide relative to each other.The arrangement is preferably such that the chambers 21, 22 are at leastsubstantially sealed from each other when the clutch 17 is fullyengaged, i.e., when the piston 19 is driven by and at the speed of theshell 4; at such time, the only flow of fluid between the chambers 21,22 is that permitted by the profiling of the friction surface 4 a and/or19 a.

[0090] The collar constituting the radially innermost portion of thepiston 19 is sealed against the peripheral surface of axial extension 15a of the hub 15 by an annular sealing element 15 c, e.g., a split ringor the like.

[0091] In order to engage the bypass clutch 17, the chamber 21 receiveshydraulic fluid from a suitable pump or another fluid source (not shown)through a channel 21 a provided in the input shaft 3 of the change-speedtransmission and in the non-illustrated transmission case within thetubular neck 5 a (radially innermost portion) of the shell 5; such neck5 a is in sealing engagement with the transmission case in a manner notshown in FIG. 1 because it forms no part of the present invention. Theshell 5 receives the pump or impeller 12 and at least a portion of thenon-rotatable stator 16. The distancing member 16 c is provided with oneor more axially parallel openings 21 b in the form of bores which canconvey pressurized fluid in order to establish a pressure differentialbetween the interiors of the chambers 21 and 22; such pressuredifferential causes the piston 19 to move axially into selected ordesired or required frictional engagement with the shell 4 (i.e., withthe housing 13). The frictional engagement entails an operation of thebypass clutch 17 without slip or with a required slip.

[0092] The pressure of fluid in the chamber 22 is caused to increasewhen the bypass clutch 17 is to be disengaged or to operate with areduced slip. This is achieved by causing the chamber 22 to receivepressurized fluid along a path defined, for example, in part by achannel or bore in the input shaft 3 and at least one channel or bore inthe profiled friction bearing 15 d between the radially innermostportion of the shell 4 and the axial extension 15 a of the hub 15. Thepressure of fluid in the just mentioned path is established by a pump(not shown) or another suitable source of pressurized fluid and mustsuffice to ensure that the pressure in the chamber 22 rises above thatin the chamber 21 so that the piston 19 is shifted axially toward theturbine 14, i.e., that the friction surface 19 is at least partiallydisengaged from the friction surface 4 a.

[0093] The piston 19 of the bypass clutch 17 can be permanently biasedin one of the two axial directions (toward or away from the turbine 14);this ensures that, when the pressure of fluid in the chamber 21 or 22matches or closely approximates that of fluid in the chamber 22 or 21,the clutch 17 is automatically engaged or fully disengaged, dependingupon the direction of uninterrupted axial stressing of the piston 19.

[0094] The torsional vibration damper 18 is installed in the power flowbetween the output shaft 2 and the hub 15 (by way of the fastenerassembly 10 and housing 13) and is active in the engaged condition ofthe bypass clutch 17. The damper 18 comprises an input 24 which isconnected with the piston 19 of the bypass clutch 17, an output 25 whichis connected with the hub 15 (in some instances with a certain freedomof angular movement), and energy storing means including (in theembodiment of FIGS. 1 to 5) an annular array of eight equidistant coilsprings 26 serving to oppose angular movements of the input 24 andoutput 25 relative to each other. The number of coil springs 26 (or ofother suitable energy storing elements) can be reduced to one, two,three and so on, or increased to nine or more.

[0095] Each spring 26 is received in a radial recess or window 27 (seeFIG. 2) at the periphery of the input 24, and each such recess isflanked by two radially outwardly extending arms 36 of the input. Thesprings 26 can be prestressed, i.e., the arms 36 can cause these springsto store energy even when the input 24 and the output 25 are permittedor caused to assume neutral positions in which the output does notinfluence the stressing of such springs. The output 25 has entrainingportions 28 which can engage the end convolutions 26 a of the adjacentcoil springs 26 to cause the springs to store additional energy inresponse to angular movement of at least one of the input 24 and output25 from its starting or neutral position in which the springs 26 are orcan be only prestressed, namely caused to store only that energy whichis imparted thereto by the respective pairs of arms 36.

[0096] The entraining portions 28 are disposed at the periphery of theoutput 25 and are obtained by removing material from the output at aradial distance from the axis X-X corresponding to that between the axisand the recesses 27 of the input 24. In order to increase the areas ofcontact between the entraining portions 28 and the adjacent endconvolutions 26 a of the respective coil springs 26, such entrainingportions can be bent in a manner best shown at 28 a in the upper half ofFIG. 1 and in FIG. 3, i.e., the radii of curvature of the bent ends 28 acan match or approximate the radii of the convolutions 26 a. The sameapplies for the radially outermost portions of the arms 36 of the input24, i.e., such radially outermost portions can be bent in the same wayas the parts 28 a so as to establish a larger-area contact with theadjacent end convolutions of the respective coil springs 26.

[0097] In order to hold the coil springs 26 against excessive movementsradially outwardly under the action of centrifugal force while the input24 and the output 25 rotate about the axis X-X, the damper 18 preferablyincludes at least one wire ring 29 which is surrounded by theconvolutions 26 a of all eight coil springs 26 (see FIG. 2). Theposition of the ring 29 is determined by locating projections 36 a (seeFIGS. 2 and 3) which constitute suitably bent portions of the input 24and engage the ring 29 from within to thus select and determine theextent to which the coil springs 26 can move radially outwardly underthe action of centrifugal force when the input 24 rotates. Thus, oncethe torque converter 1 is assembled and installed between the shafts 2and 3, the position of the ring 29 is fixed by the locating projections36 a of the input 24. It is preferred that the locating projections 36 afurther serve to fix the position of the ring 29 in the axial directionof the housing 3.

[0098]FIG. 3 shows that the inner diameters D of the convolutions 26 a(i.e., the diameter of the compartment or space 26 b surrounded by theconvolutions 26 a of a coil spring 26) can equal or approximate 2 dwherein d is the diameter of the wire of which the ring 29 is made. Itis presently preferred to employ a wire having a diameter d which isslightly greater than one half of the inner diameter of a convolution 26a. The ends of this wire can be welded (at 29 a) to each other.Alternatively, one of these ends can be provided with a hook (not shown)and the other end can be provided with an eyelet for the hook; suchsolution is preferred if it is anticipated that the ring 29 willnecessitate replacement or temporary removal during the useful life ofthe torque converter 1. The wire of the ring 29 can be bent to resembleits utimate shape (shown in FIG. 2) prior to causing it to pass throughthe internal spaces 26 b of the coil springs 26.

[0099] The locating projections 36 a of the input 24 can be providedwith slits 36 c (shown in each of FIGS. 2 and 3) which reduce thestiffness of the arms 36 as seen in the axial direction of the input 24.The ratio of d to D is or can be determined by the relationship orequation 0.8*D>d>0.2*D, preferably 0.6*D>d>0.3*D. The arrangement can besuch that the wire of the ring 29 contacts the convolutions 26 a of thecoil springs 26 at its radially innermost as well as at its radiallyoutermost portions. In all instances D>d and preferably D>d>0.25 D, mostpreferably 0.66D>d>0.25D. As concerns the diameter of the ring 29, it ispreferably selected in such a way that this ring contacts the radiallyinnermost portions of the convolutions 26 a of all coil springs 26 whenthe ends of the wire of the ring 29 are secured to each other at 29 a.In other words, and as shown in FIGS. 2 and 3 the ring 29 can bedimensioned to ensure that the springs 26 have a minimal radialclearance or play s (see FIG. 3) relative to the surfaces 27 asurrounding the radially outermost portions of the recesses 27. Suchdimensioning of the ring 29 reduces the likelihood of excessive wearupon the coil springs 26 due to engagement with the input 24 duringcompression of the springs as a result of turning of the input relativeto the output 25 and/or vice versa.

[0100] The input 24 of the damper 18 is affixed to the piston 19 of thebypass clutch 17 at points established by a circular array of rivets 30.The shanks of such rivets extend through openings 36 b which areprovided in the arms 36 of the input 24 radially outwardly of the coilsprings 26. The output 25 has an internal gear 31 mating with anexternal gear (spur gear) on the extension 15 a of the hub 15. Thesemating internal and external gears preferably mesh with a certain playto ensure that the output 25 is mounted on the axial extension 15 a witha certain angular play. In other words, the mating gears of the output25 and extension 15 a ensure that the damper 18 becomes effective with acertain delay.

[0101] The extent of angular movability of the input 24 and output 25 ofthe damper 18 is determined by the rivets 32 (FIG. 1) each of which isrigidly affixed to the input 24 and each of which extends into anarcuate circumferentially extending slot 33 of the output 25. Thelengths of the slots 33 (as seen circumferentially of the radially innerportions of the input 24 and output 25) determine the extent to whichthe input and the input can turn relative to each other about the axisX-X of the housing 13.

[0102] The slots 33 and the rivets 32 can be omitted if the torsionalvibration damper 18 is set up to limit the extent of angular movabilityof the input 24 and output 25 relative to each other solely under theaction of coil springs 36. Thus, the angular movability of the input 24and output 25 relative to each other from their neutral positions can beterminated when the convolutions of at least one of the coil springs 26come into actual abutment with each other, i.e., when the at least onecoil spring 26 begins to act as a solid block. In such instance, theconvolutions 26 a of the coil springs 26 can be provided with jackets orcoats of a suitable elastomeric material.

[0103]FIG. 1 further shows a safety ring 34 which is disposed betweenthe left-hand heads of the rivets 32 and the adjacent side of the output25; the purpose of the safety ring 34 (the illustrated safety ring is aflat annular disc resembling a washer) is to prevent penetration of theleft-hand heads of the rivets 32 into the respective arcuate slots 33 ofthe output 25.

[0104] The input 24 and the output 25 of the damper 18 are urged apartin the axial direction of the housing 13 by additional resilient means35 shown in FIG. 1 in the form of a membrane- or diaphragm (Belleville)spring which urges the output against the safety ring 34. This resilientmeans 35 opposes angular movements of the input 24 and output 25relative to each other while the parts 24, 25 move in directions tostress the coil springs 26 as well as while the springs 26 are permittedto dissipate some energy.

[0105] The illustrated torsional vibration damper 18 can be utilizedwith advantage in many types of torque converters, i.e., not only inthose shown in the drawing and described in the specification of thepresent application. Furthermore, the torque converter 1 can employseveral torsional vibration dampers, for example, the damper 18 and asecond damper between the turbine 14 and the hub 15.

[0106] The rivets 30 connect the piston 19 of the bypass clutch 17 withthe arms 36 radially outwardly of the plate-like central portion or body24 a of the input 24. The arms 36 can be pivoted relative to the body 24a, i.e., the rivets 30 can move (within limits) relative to the body 24a in the axial direction of the housing 13. FIG. 2 shows that thesurfaces bounding each recess 27 can be disposed at least substantiallyat right angles to each other. Each arm 36 of the input 24 shown in FIG.2 has a trapezoidal shape and tapers radially inwardly toward the centerof the input body 24 a. This ensures that the rigidity of each arm 36decreases radially inwardly toward the junction with the body 24 a. Inother words, the flexibility of each arm 36 decreases in a directiontoward the axis X-X. Such arrangement is desirable because it reducesthe likelihood of breakage of the arms in the regions of the rivets 30,especially due to fatigue in response to axial and/or other stressingduring repeated engagement and disengagement of the bypass clutch 17 aswell as while the bypass clutch is at least partly engaged. Stillfurther, such configurations of the arms 36 exert a positive influenceupon the piston 19 of the bypass clutch 17, especially in the regions ofthe rivets 30.

[0107] It is also within the purview of the present invention to providethe arms 36 with slots extending from the respective openings 36 btoward or to the body 24 a of the input 24 to thus enhance theelasticity of the input. Analogously, the piston 19 can be provided withslots extending radially outwardly to the rivets 30 to thus enhance itselasticity and to prolong its useful life. The provision of locatingprojections 36 a which constitute bent portions of the arms 36 alsocontributes to flexibility of the respective (radially inner orinnermost) portions of such arms.

[0108] The piston 19 need not be directly connected with the input 24;for example, the bypass clutch 17 or an equivalent thereof can comprisea washer or an analogous part which is rigid with the input and isconnected to the piston 19 with limited freedom of axial movement, e.g.,due to elasticity of the piston and/or washer.

[0109] Furthermore, the torque converter 1 can comprise two or even moredampers, e.g., the damper 18 and a second damper between the turbine 14and the hub 15 of the torque converter. The arrangement is or can besuch that, when the bypass clutch 17 is engaged, torque can betransmitted directly from the housing 13 to the hub 15 so that the pump12 and the turbine 14 are bypassed. On the other hand, when the bypassclutch 17 is disengaged, torque is transmitted from the housing 13,through the pump 12, body of hydraulic fluid in the housing 13 andturbine 14 on to the hub 15. The transmission of torque from the housing13 to the hub 15 can take place along two paths if the bypass clutch isonly partly engaged, i.e., when the piston 19 frictionally engages butis free to slide relative to the shell 4 of the housing 13. An advantageof the torque converter 1 is that a single torsional vibration damper 18suffices to damp vibrations of torque regardless of whether such torqueis being transmitted only via pump 12, only via bypass clutch 17, oralong each such path.

[0110] The ring 29 exhibits the advantage that it renders it possible toachieve substantial savings in space in the axial and radial directionsof the torque converter 1. This will be readily appreciated by takinginto consideration that the ring 29 occupies space (within the coilsprings 26) which would otherwise remain unoccupied. Moreover, the ring29 does not interfere with confinement of springs 26 in discreterecesses 27 between the radially outwardly extending arms 36 of theinput 24. The properly installed ring 29 can be held against undesirablestray movements in any desired direction such as radially outwardly,radially inwardly and/or axially of the input 24. The locatingprojections 36 a constitute but one of several means which can beutilized to prevent stray movements of the ring 29. The provision ofprojections 36 a and of their slits 36 c exhibits the advantage thatthey contribute to axial flexibility or yieldability of the input 24(i.e., more than separately produced projections which are welded to theinput 24 radially inwardly of the ring; such separately producedprojections would actually increase the rigidity of the input 24).

[0111] The arms 36 are or can be configurated to ensure that they cancooperate with the portions 28 a of the output 25 to properly engage andstress commercially avaliable coil springs. Thus, the confronting edgefaces of neighboring arms 36 are or can be parallel to each other.

[0112] It is within the purview of the present invention to provide theprojections 7 on the disc 6 and to provide the openings 6 b in the mass8 or in another part of or borne by the housing 13. The same holds truefor the interchangeability of positions of the snap fastener 9 d and theopening or openings 6 c. Such snap fastener permits, if and whennecessary, for convenient detachment of the torque converter 1 from theshaft 2. It is also possible to employ snap fasteners in the form ofsplints which can enter openings in the projections 7 by snap actionand/or otherwise.

[0113]FIGS. 6 and 7 illustrate the torsional vibration damper 118 andthe piston 119 of a modified torque converter. The piston 119 is securedto the input 124 of the damper 118 by an annular array of rivets 130.The input 124 comprises two walls 124 b, 124 c which flank the output125 of the damper 118 and the marginal portion of each of which issecured to the piston 119 by the rivets 130. Such rivets are locatedradially outwardly of the friction surface 119 a of the piston 119.

[0114] The marginal portions of the walls 124 b, 124 c of the input 124are not profiled, i.e., they are not provided with radial extensionscorresponding to the arms 36 of the input 24. However, and in order toensure adequate elasticity (axial flexibility) of such walls, theirplate-like central bodies 124 a′, 124 a″ are partially separated fromthe rivet-receiving marginal portions 136 a by suitably configuratedstiffness-reducing windows or slits 137 and 138, respectively.Additional cutouts or slits can be provided to enhance the flexibilityof certain other portions of the plate-like body 124 a′ and/or 124 a″.Each of the illustrated stiffness-reducing slits 137, 138 issubstantially U-shaped and partially surrounds the respective rivet 130.The central portions of the slits 137, 138 are narrower than their endportions, and such end portions are or can be located at the same radialdistance from the axis of the damper 118 as the rivets 130.

[0115] The walls 124 b, 124 c of the composite input 124 (as well as theplate-like body or wall 24 a of the input 24 of the damper 18) arepreferably made by resorting to a deep drawing, stamping of pressing(molding) technique. It is often advisable to provide the slits 137, 138in the blanks which are to be converted into the walls 124 b, 124 cprior to the final shaping procedure, i.e., prior to imparting to thesewalls configurations (curvatures) corresponding to those shown in FIG.6, e.g., by resorting to a potting or an analogous technique. Thissimplifies the formation of slits 137, 138 because these slits can beformed in the blanks for the walls 124 b, 124 c while the blanks arestill flat.

[0116]FIG. 7 shows that the slits 137 are closed at their ends, i.e.,that they do not extend all the way to the peripheral surface of thewall 124 b. The same applies for the windows or slits 138 in the wall124 c. On the other hand, FIG. 8 illustrates a modification wherein oneend portion of the slit or recess or window 137 is open, i.e., such openend portion extends radially outwardly beyond the rivet 130 and all theway into the peripheral surface of the illustrated input wall 224 b.This results in the making of a tongue 236 which extendscircumferentially of the wall 224 b and is secured to the piston 119 ofthe associated bypass clutch by the illustrated rivet 130. An advantageof the structure which is shown in FIG. 8 is that the wall 224 b and thetongue 236 are movable relative to each other axially (i.e., at rightangles to the plane of FIG. 8) and that the tongue 236 can also have acertain freedom of radial movement relative to the common axis of thewall 224 b and piston 119.

[0117] Referring again to FIGS. 6 and 7, the composite input 124 a+124 band the output 125 of the damper 118 can turn relative to each otherabout their common axis under the bias or against the opposition ofenergy storing means including an annular assembly of coil springs 126.Each coil spring 126 is a composite coil spring in that it includes anouter spring 126 a and an inner spring 126 b confined in the respectiveouter spring. The springs 126 a are received in windows 127 a, 127 b ofthe walls 124 b, 124 c and in windows 128 provided in the output 125.When the input 124 a, 124 b and the output 125 are caused to turnrelative to each other, the radially extending surfaces flanking thewindows 127 a, 127 b, 128 bear upon the end convolutions of and stressthe respective composite coil springs 126.

[0118] The reference characters 129 a, 129 b denote flaps or extensionsrespectively provided on the walls 124 b, 124 c of the composite inputto limit the extent of movability of the composite coil springs 126radially outwardly, e.g., under the action of centrifugal force. Theshapes of the radially inwardly facing surfaces of the flaps 129 a, 129b preferably conform or substantially conform to the adjacent portionsof external surfaces of convolutions forming part of the larger-diametercoil springs 126 a.

[0119] The extent of angular movability of the input 124 b, 124 c andthe output 125 of the damper 118 relative to each other is determined bya projection 139 constituting a substantially axially depressed portionof the wall 124 c and received in a recess 133 of the output 125. Thelength of the recess 133 (as seen in the circumferential direction ofthe damper 118) determines the extent of angular movability of the input124 b, 124 c and output 125 relative to each other; this recess islonger than the projection 139 (again as seen in the circumferentialdirection of the damper).

[0120] The damper 118 can be provided with two or more circumferentiallyspaced apart projections 139 and with an equal nuber of recesses 133,one for each projection 139. Furthermore, similar or analogous means forlimiting the angular movements of the input and output of the torsionalvibration damper relative to each other can be employed in the torqueconverter 1 of FIGS. 1 to 5 as well as in other torque converters whichare described and shown in the specification and drawing of the presentapplication. Still further, similar means for limiting angular movementsof two or more parts which are turnable relative to each other about acommon axis and whose turnability must be limited with a high degree ofaccuracy and reliability can be employed in conventional torqueconverters or in numerous other apparatus.

[0121] The projection 139 of the wall 124 c can be replaced with a part(such as a tongue or pin or the like) which is a separately producedelement and is welded or otherwise affixed to the wall 124 c.

[0122]FIG. 6 further shows a resilient energy storing element or device135 which is a diaphragm spring or a membrane and serves to bias thewall 124 b axially and away from the output 125, i.e., away from thewall 124 c. The means for ensuring that the diaphragm spring 135 sharesthe angular movements of one of the input 124 b, 124 c and output 125relative to the other of these components of the damper 118 comprises atongue 135 a provided on the diaphragm spring 135 and extending into oneof the recesses 133 or into a discrete recess or window 133 a of theoutput 125. Thus, the diaphragm spring 135 is compelled to share allangular movements of the output 125 relative to the input 124 b, 124 c.

[0123] The diaphragm spring 135 further serves as a means for yieldablyopposing turning of the input 124 b, 124 c and output 125 relative toeach other. If the damper 118 is to permit a certain amount of angularmovement of the input 124 b, 124 c and output 125 relative to eachother, the opening 133 a is dimensioned to receive the tongue 135 a ofthe diaphragm spring 135 with a preselected amount of play in thecircumferential direction of the damper 118. Such arrangement ensuresthat the friction between the diaphragm spring 135 and the input 124 b,124 c and/or output 125 becomes effective with a preselected delayfollowing initial angular displacement of the input and output relativeto each other. Such delayed friction can be resorted to in the damper118 as well as in the damper 18 and in other dampers which can beutilized in torque converters embodying the present invention.

[0124] The slots 137 and/or 237 can be formed in the blanks which arethereupon converted into the input wall 124 b or 224 b by resorting to astamping procedure. However, it is also possible to provide such slotsin a partly finished (shaped) wall 124 b or 224 b. Still further, it ispossible to provide the blanks which are to be converted into the walls124 b and/or 224 b with simple slits and to thereupon deform (such asselectively widen) these slits during certain stages of conversion(shaping) of blanks into finished walls 124 b and/or 224 b. This can bereadily achieved by providing the slits in those portions of a blank forthe wall 124 b or 224 b which are thereupon flexed, upset and/orotherwise curved as can be seen, for example, in the region of the slot137 in the upper portion of FIG. 6.

[0125]FIG. 9 shows a damper 318 which is similar to the damper 118 ofFIGS. 6 and 7. The wall 324 b of the input 324 of the damper 318 isnon-rotatably affixed to the piston 119 of a bypass clutch by rivets 130occupying an annular array of points or locations as seen in thecircumferential direction of the radially outermost (marginal) portionof the piston. The wall 324 b of the input 324 is provided with slots orwindows 337 a which are not identical with the slots or windows 337 bprovided in the other wall (not shown in FIG. 9) of such compositeinput. The other wall of the input 324 is located behind the wall 324 b.The reason for differences between the slots 327 a and 327 b is that,under certain circumstances, axial flexibility of one wall of the inputshould deviate from that of the other wall, especially if the two wallsare not identical. It has been found that the flexibility of the wallsforming part of an input should depend or preferably depends upon theirdimensions and/or other parameters.

[0126] In FIG. 9, the slots 337 a are longer (as seen circumferentiallyof the piston 119) than the slots 337 b. In other words, axialflexibility of the flaps 336 a forming part of the wall 324 b exceedsthat of the flaps on the other wall of the input 324.

[0127]FIG. 10 illustrates a portion of an input 424 forming part of adamper resembling the damper 118 of FIGS. 6 and 7. In order to enhanceaxial flexibility in the regions between the central portion of the discor wall 424 a and the radial arms 436 which are flanked by the slots437, the radially outer ends of these slots are open, i.e., they extendall the way to the peripheral surface of the disc 424 a. In addition,each slot 437 a extends substantially exactly radially inwardly and hasan enlarged radially innermost portion bounded by a circular surface.The openings 130 a are provided in the arms 436 and serve to receiverivets (not shown) which secure the disc 424 a to the other disc or wall(not shown) of the input 424. The openings 130 a are or can be providedmidway or substantially midway between the neighboring keyhole-shapedslots 437.

[0128] An advantage of the input 424 of FIG. 10 is that it permits oftendesirable and necessary wobbling vibratory movements of the disc 424 arelative to the output (not shown) of the damper in the torque converterembodying the structure of FIG. 10. Thus, neighboring arms 436 of thewall 424 a have a limited freedom of movement in a direction at rightangles to the plane of FIG. 10. This reduces the likelihood ofdevelopment of excessive stresses in the torque converter embodying thestructure of FIG. 10. Excessive stresses could cause cracking of thedisc or wall 424 a in the regions of the openings 130 a.

[0129] An advantage of keyhole-shaped recesses or slots 437 is that oneavoids the formation of pronounced severed or stamped edges. Moreover,the likelihood of fatigue in regions where the arms 436 are repeatedlyflexed relative to the central portion or wall 424 a of the input 424 isremote, and the same holds true as concerns the development of cracks atthe radially inner ends of the keyhole-shaped recesses 437. Similarresults can be obtained if the sharply defined corners 36 f of therecesses 36 shown in FIG. 2 are replaced with much less or at leastsomewhat less pronounced corners bounded by concave edge faces of thecentral portion 24 a and the arms 36 of the input 24.

[0130]FIG. 11 illustrates a portion of an input 524 having a disc orwall 524 a with an undulate peripheral surface bounding an annular arrayof recesses 537 the length of each of which decreases gradually towardthe axis of the damper including the input 524. The arms 537 a alternatewith the recesses 537 and each such arm has an opening 130 a for a rivet(not shown in FIG. 11) which secures the disc or wall 524 a to the otherdisc or wall (not shown) of the input 524. The radially innermostportions 537 b of the recesses 537 are bounded by concave portions ofthe peripheral surface of the wall 524 a.

[0131] An advantage of the input 524 is that the lengths of the recesses537 (as measured in the circumferential direction of the input) canequal or even exceed the lengths of the arms 537 a. This even furtherreduces the likelihood of premature cracking of and/or other damage tothe input 524 in response to repeated axial flexing of the arms 537 aand the central portion 524 a relative to each other.

[0132] An advantage of arms of the type shown at 36 in FIG. 2 over arms537 a is that the radially outwardly extending edge faces of the arms 36can lie flush against the adjacent end convolutions 26 a of the coilsprings 26. Regardless of their exact shapes, the arms of all inputs canbe slotted and/or otherwise influenced to increase their flexibility inthe axial direction of the respective torsional vibration damper.

[0133] FIGS. 12 to 14 illustrate certain features of a further hydraulictorque converter 601 having a housing 613 composed of two partiallyinterfitted shells or walls 604 and 605. A pump or impeller 612 isinstalled in and rotates with the shell 605; this pump can circulate abody of hydraulic fluid which, in turn, can rotate a turbine 614extending in part into the interior of the shell 604. The latter isconnected to the output shaft 602 of the prime mover in the power trainof a motor vehicle, e.g., without the interposition of a disccorresponding to the disc 2 in the torque converter 1 of FIG. 1. Thehousing 613 constitutes the input of the torque converter 601.

[0134] The output element of the torque converter 601 is constituted byor includes a hub 615 having an internal gear 603 a mating with anexternal gear on the input shaft of the change-speed transmission (notshown in FIGS. 12 to 14). The torque converter 601 further comprises abypass clutch 617 which, when engaged, transmits torque directly betweenthe housing 613 and the hub 615. When the clutch 617 is disengaged, thetransmission of torque takes place from the housing 613 to the hub 615by way of a torsional vibration damper 618; this mode of operationdeparts from that of the torque converter 1 shown in FIG. 1.

[0135] In order to connect the damper 618 to the turbine 614, the latteris rotatably mounted on the hub 615 and, to this end, the turbinecarries a discrete hub 615 a which is non-rotatably connected with theturbine. The hub 615 a is rotatable on the hub 615 and is sealinglysecured thereto by a sealing ring 615 b. A radially extending collar 615c constitutes an axial stop for the hub 615 a and its radially outermostportion non-rotatably carries the output 625 of the torsional vibrationdamper 618. That side of the stop 615 c which faces away from the hub615 a for the turbine 614 is surrounded by a sleeve constituting theradially outermost portion of the piston 619 which forms part of thebypass clutch 617. The sleeve of the piston 617 is rotatable on and ismovable axially of the hub 615 and surrounds a sealing ring 615 d whichis recessed in this hub.

[0136] The input 624 of the damper 618 has an internal gear 624 a whichmates with a complementary (spur) gear on an axial projection 615 a′ ofthe discrete hub 615 a for the turbine 614. The energy storing means 626of the damper 618 opposes rotation of the input 624 and output 625relative to each other, and the input 624 is axially movably connectedwith the piston 614 of the bypass clutch 617. It will be noted that theaxial projection 615 a′ is located radially outwardly of the collar 615c for the output 625. In accordance with a feature of the inventionembodied in the torque converter 601, the axial rigidity of the input624 of the damper 618 is pronounced, i.e., an axially yieldable input isreplaced with the axially rigid or stiff input 624 and the torqueconverter 601 further comprises discrete resilient means 637 installedbetween the input 624 and the piston 619.

[0137]FIG. 13 shows one of the resilient means 637; it constitutes aleaf spring which is riveted to the piston at 630 and to the input 624at 630 a. This leaf spring 630 is but one of an annular array orassembly of such leaf springs which permit limited axial movements ofthe piston 619 relative to the axially rigid input 624. Discrete rivets630 and/or 630 a can be replaced with rivet-shaped formations (displacedportions) of the input 624 and/or piston 619. The heads of suchformations resemble and act as rivet heads; they are anchored in the endportions of the leaf springs 637.

[0138]FIG. 14 shows that the torque converter 601 further comprises atleast one axial stop 624 c which serves to maintain the piston 619 at aselected axial distance from the input 624 of the damper 618; theillustrated stop 624 c of FIG. 14 is an integral part of the input 624.It is normally preferred to employ an annular arrangement of severaldiscrete axial stops 624 a. The character 624 d denotes in FIG. 14 awindow which is provided in the input 624 and affords access to therivet 613. The input 624 is provided with several windows 624 d, one foreach of the rivets 630.

[0139] Referring again to FIG. 12, the output 625 of the damper 618separates the input 624 from a washer 640. The radially outer portionsof the input 624 and the washer 640 are welded and/or riveted to eachother between neighboring springs 626 or radially outwardly of suchsprings. Each spring 626 is a composite resilient element including anouter coil spring and an inner coil spring which is confined in theouter coil spring. Each such composite coil spring 626 is received inpart in one of the windows 627 a provided in the input 624, in one ofthe windows 627 b provided in the output 625, and in one of the windows628 provided in the washer 640. Such mounting compels the springs 626 tostore energy when the input 624 and the washer 640 are caused to turnrelative to the output 625 and/or vice versa.

[0140] Friction generating devices 633 anchored in the input 624 andbearing upon the output 625 generate friction when the parts 624, 625are caused to turn relative to each other. Each device 633 (only oneshown in FIG. 12) is or can constitute a leaf spring which is installedto bias the output 625 axially and away from the input 624 and/or viceversa.

[0141] The packages 626 of coil springs are held against excessivemovement radially outwardly (e.g., under the action of centrifugalforce) by abutments 629 a and 629 b respectively provided on the washer640 or output 625 and input 624. Each abutment 629 b is shown as anintegral part of the input 624. On the other hand, each abutment 629 ais or can constitute a separately produced part which is affixed to theoutput 625 or to the washer 640.

[0142] The rivets 630 and/or 630 a can be replaced with screws, boltsand nuts and/or other types of fasteners without departing from thespirit of our invention. The utilization of rivets which are of onepiece with the piston 619 or with the input 624 is preferred in manyinstances because this entails a substantial reduction of the overallnumber of parts in the torque converter 601.

[0143] The leaf springs 637 can be installed radially inwardly of thesprings 626 or at the same radial distance from the axis X-X; in thelatter case, the leaf springs 637 can alternate with the springs 636 asseen in the circumferential direction of the damper 618.

[0144] It is also possible to install the damper 618 axially between thehousing 613 and the piston 619 or axially between the piston and theturbine 614 (this is actually shown in FIG. 12).

[0145] The springs of the damper can constitute expansion or compressionsprings.

[0146]FIG. 15 shows a further improved hydraulic torque converter 700which includes an impeller or pump (not visible in that portion of thetorque converter which is shown in FIG. 15), a turbine 701 in a housing703, and a stator 702 between the pump and the turbine. A torsionalvibration damper 704 and a bypass clutch 705 are also provided in thehousing 703. The damper 704 comprises essentially an input composed oftwo disc-shaped members or walls 706, 707 having radially outermostportions which are riveted or otherwise affixed to each other and areprovided with windows for energy storing elements. A flange-like output750 of the damper 704 is disposed between the disc-shaped members 706,707 of the input and its radially innermost portion is of one piece withan output element or hub 751; however, it is equally possible to employseparately produced parts 750, 751 which are welded or otherwisereliably affixed to each other.

[0147] The member 706 of the input of the damper 704 is installedbetween the turbine 701 and the output 750 and is connected with (suchas riveted to) an adapter 752 having an internal gear 708 mating with aspur gear 755 of the hub 751 with a certain play at least matching themaximum required angular movability of the input 706, 707 and output 750of the damper 704 relative to each other.

[0148] A hub 760 is connected with a casing 701 a of the turbine 701,e.g., by welding, by rivets or by resorting to a friction fit. That sideof the hub 760 which confronts the damper 704 is provided with axiallyparallel extensions 761 (e.g., with an annular arrangement ofequidistant extensions) which are received in complementary recesses 762of the adapter 752, preferably at least substantially without play. Theadapter 752 serves to connect the turbine 701 with the disc or wall 706of the input of the damper 704, i.e., the latter is mounted to dampvibrations of the turbine as well as vibrations of the bypass clutch705. It is to be noted that the turbine hub 760 is turnable relative tothe hub 751.

[0149] The adapter 752 is connected to the part 706 of the input of thedamper 704 by two annuli of rivets. The outer annulus includes rivets770, and the inner annulus includes rivets 771. The arrangement can besuch that the rivets 770 are offset relative to the rivets 771 in thecircumferential direction of the adapter 752; this reduces the tensionalstresses between the adapter and the input 706, 707 of the damper 704.

[0150] An advantage of the adapter 752 is that it can be utilized toconnect any one of several types of dampers with any one of severaltypes of turbines, i.e., it is possible to select (for use in the torqueconverter 700 or in another torque converter) any one of several typesof torsional vibration dampers and any one of several types of turbinesby resorting to the building block construction principle of FIG. 15.

[0151] Without further analysis, the foregoing will so fully reveal thegist of the present invention that others can, by applying currentknowledge, readily adapt it for various applications without omittingfeatures that, from the standpoint of prior art, fairly constituteessential characteristics of the generic and specific aspects of theabove outlined contribution to the art of torque converters and,therefore, such adaptations should and are intended to be comprehendedwithin the meaning and range of equivalence of the appended claims.

What is claimed is:
 1. A hydraulic torque converter, comprising: ahousing arranged to rotate about a predetermined axis, to confine asupply of hydraulic fluid and to receive torque from an output elementof a prime mover; a pump disposed in and arranged to rotate with saidhousing about said axis; an annular turbine coaxial with said pump,disposed in said housing and arranged to receive torque from the fluidin said housing in response to rotation of said pump; a rotary inputelement coaxial with said housing; a rotary output member arranged totransmit torque between said input element and at least one of saidpump, said turbine and said housing; a bypass clutch engageable totransmit force between said pump and said turbine during predeterminedstages of operation of the torque converter; and at least one torsionalvibration damper in a power flow between said housing and said outputmember, including an input, an output coaxial with said housing and saidinput and rotatable relative to said input, and energy storing meansarranged to oppose rotation of said input and said output relative toeach other.
 2. The torque converter of claim 1, wherein said prime moverincludes an engine and said output element includes a shaft of theengine, and further comprising a stator in said housing between saidpump and said turbine.
 3. The torque converter of claim 1, wherein saidinput element includes a shaft of an automatic change-speedtransmission.
 4. The torque converter of claim 1, wherein said bypassclutch includes a substantially disc-shaped member and furthercomprising means for resiliently connecting said disc-shaped member tosaid input with freedom of movement in the direction of said axis. 5.The torque converter of claim 4, wherein said substantially disc-shapedmember includes a piston.
 6. The torque converter of claim 5, furthercomprising a force-locking connection between said piston and saidhousing.
 7. The torque converter of claim 1, wherein said bypass clutchincludes a member connected with one of said input and said output at aplurality of points spaced apart from each other in a circumferentialdirection of said turbine, said one of said input and said output andsaid member of said bypass clutch which are connected to each other atsaid plurality of points being provided with means disposed at least inpart radially inwardly of said points and arranged to reduce thestiffness of said at least one of said input and output and said memberof said clutch, as seen in the direction of said axis.
 8. The torqueconverter of claim 7, wherein said stiffness reducing means includes anannular array of recesses in said at least one of said input, saidoutput and said member of said bypass clutch.
 9. The torque converter ofclaim 8, wherein said recesses are adjacent said points.
 10. The torqueconverter of claim 9, wherein each of said recesses includes an arcuateslit partially surrounding a different one of said points.
 11. Thetorque converter of claim 10, wherein each of said slits includes firstand second end portions and at least one of said end portions has awidth exceeding that of an intermediate portion of the respective slit.12. The torque converter of claim 10, wherein each of said recessesincludes an end portion extending radially outwardly beyond at least oneof said points.
 13. The torque converter of claim 9, wherein saidrecesses include slits provided in said input and said input includes aradially outermost portion, each of said slits having an open end atsaid radially outermost portion of said input.
 14. The torque converterof claim 9, wherein each of said recesses includes a slit and each ofsaid slits has an enlarged end disposed at a first radial distance fromsaid axis, said points being located at a second radial distance fromsaid axis and said second radial distance at least approximating saidfirst radial distance.
 15. The torque converter of claim 7, wherein saidstiffness reducing means is provided in said input at a first stage ofassembly of said damper with said housing and said output member, saidinput undergoing a shaping during a second stage following said firststage of assembly of the damper.
 16. The torque converter of claim 1,wherein said at least one damper is provided in a power flow betweensaid bypass clutch and said output member.
 17. The torque converter ofclaim 1, wherein said at least one damper is disposed in a power flowbetween said turbine and said rotary output member.
 18. The torqueconverter of claim 1, wherein said input of said torsional vibrationdamper comprises at least two walls and further comprising means forconnecting at least one of said walls with a member of said bypassclutch.
 19. The torque converter of claim 1, wherein said bypass clutchincludes a portion adjacent a portion of said damper and furthercomprising an annular array of fasteners spacedly surrounding said axisand connecting said portions of said bypass clutch and said damper toeach other, and further comprising means for reducing the stiffness ofat least one of said portions in the axial direction of said housingincluding recesses provided in at least one of said portions adjacentsaid fasteners.
 20. The torque converter of claim 19, wherein saidrecesses are open as seen radially outwardly away from said axis andclosed radially inwardly of neighboring fasteners.
 21. The torqueconverter of claim 19, wherein said recesses alternate with saidfasteners.
 22. The torque converter of claim 21, wherein the widths ofat least some of said recesses—as seen in the circumferential directionof said portions—increase in a direction toward said axis.
 23. Thetorque converter of claim 20, wherein said recesses include closedradially inner end portions closest to said axis and bounded by at leastsubstantially circular surfaces of said at least one portion.
 24. Thetorque converter of claim 20, wherein the widths of at least some ofsaid recesses—as seen in the circumferential direction of saidportions—decrease in a direction toward said axis.
 25. The torqueconverter of claim 24, wherein said at least one portion has an undulateperipheral surface and said recesses are provided in said peripheralsurface.
 26. The torque converter of claim 1, wherein said bypass clutchcomprises a first portion and said damper includes a second portion, andfurther comprising springs connecting said first portion with saidsecond portion with limited freedom of movement in the direction of saidaxis.
 27. The torque converter of claim 26, wherein said springs includean annular array of leaf springs spacedly surrounding said axis.
 28. Thetorque converter of claim 26, wherein said second portion includes saidinput of said damper.
 29. The torque converter of claim 26, furthercomprising means for non-rotatably connecting said input of said damperwith said turbine.
 30. The torque converter of claim 26, wherein saidfirst portion includes a piston of said bypass clutch.
 31. The torqueconverter of claim 30, wherein said piston and said housing includeannular portions frictionally contacting each other in the engagedcondition of said bypass clutch, said springs including leaf springsconnecting said input with a radially outermost part of said portion ofsaid clutch.
 32. The torque converter of claim 1, wherein said energystoring means includes an annulus of coil springs and means for limitingthe movability of said coil springs radially of said axis.
 33. Thetorque converter of claim 32, wherein said means for limiting includes aring and said springs have convolutions surrounding said ring withlimited freedom of movement of said springs and said ring relative toeach other radially of said axis.
 34. The torque converter of claim 33,further comprising means for connecting said ring to said damper. 35.The torque converter of claim 34, wherein said ring is connected to oneof said input and said output.
 36. The torque converter of claim 34,wherein said ring is connected with the input of said damper.
 37. Thetorque converter of claim 33, wherein said ring consists of a materialselected from the group consisting of metallic and plastic substances.38. The torque converter of claim 32, wherein said means for limitingincludes a preshaped annular member and said coil springs haveconvolutions spacedly surrounding said preshaped annular member.
 39. Thetorque converter of claim 38, wherein said annular member includes endportions which are affixed to each other by at least one of theundertakings including bonding, hooking and nesting.
 40. The torqueconverter of claim 38, wherein at least one of said input and saidoutput includes means for locating said annular member relative to saidinput and said output in at least one of directions including radiallyof said axis and in the direction of said axis.
 41. The torque converterof claim 40, wherein said locating means includes an annular array ofdiscrete projections provided on said at least one of said input andsaid output.
 42. The torque converter of claim 41, wherein said annularmember is tensioned by said projections.
 43. The torque converter ofclaim 41, wherein said discrete projections include deformed portions ofsaid input.
 44. The torque converter of claim 33, wherein said ring is awire with a diameter d, said convolutions have inner diameters D and theratio of d to D is determined by the relationship 0.8*D>d>0.2*D.
 45. Thetorque converter of claim 33, wherein said ring is a wire with adiameter d, said convolutions have inner diameters D and the ratio od dto D is determined by the relationship 0.6*D>d>0.3*D.
 46. The torqueconverter of claim 1, wherein said energy storing means includes aplurality of springs each received in a recess of said input, said inputfurther having at least substantially radial arms alternating with saidrecesses as seen in a circumferential direction of said damper and saidoutput including entraining portions cooperating with said arms tostress said springs in response to rotation of at least one of saidinput and said output relative to the other thereof.
 47. The torqueconverter of claim 46, wherein at least one of said arms and saidentraining portions has surfaces at least partially conforming to thesurfaces of adjacent portions of said springs.
 48. The torque converterof claim 46, wherein at least one of said springs is installed instressed conditions between two of said arms.
 49. The torque converterof claim 46, wherein at least one of said springs is installed instressed condition between two of said entraining portions.
 50. Thetorque converter of claim 46, wherein said recesses are bounded bysurfaces provided on said input and making right angles with each other.51. A hydraulic torque converter, comprising: a housing including a massand arranged to rotate about a predetermined axis, to confine a supplyof hydraulic fluid and to receive torque from an output element of aprime mover; a pump disposed in and arranged to rotate with said housingabout said axis; an annular turbine coaxial with said pump, disposed insaid housing and arranged to receive torque from the fluid in saidhousing in response to rotation of said pump; a rotary input elementcoaxial with said housing; a rotary output member arranged to transmittorque between said input element and at least one of said pump, saidturbine and said housing; a bypass clutch engageable to transmit forcebetween said pump and said turbine during predetermined stages ofoperation of the torque converter; at least one torsional vibrationdamper including an input, an output coaxial with said housing and withsaid input and rotatable relative to said input, energy storing meansarranged to oppose rotation of said input and said output relative toeach other, and a torque transmitting member between said input and saidoutput element; an annular array of retaining members provided on saidmass and received in openings provided therefor in said torquetransmitting member; and means for holding said retaining members in therespective openings.
 52. The torque converter of claim 51, wherein saidretaining members include pins at least substantially parallel to saidaxis and having end portions extending through the respective openings,said holding means engaging said end portions of said pins.
 53. Thetorque converter of claim 52, wherein said holding means extend at leastsubstantially circumferentially of said torque transmitting member. 54.The torque converter of claim 51, wherein said holding means includes aring-shaped support and discrete holding members provided on saidring-shaped support and each engaging one of said retaining members. 55.The torque converter of claim 51, wherein said torque transmittingmember is disposed between the prime mover and said mass, as seen in thedirection of said axis.
 56. The torque converter of claim 51, wherein atleast one of said retaining members has a substantially conical shapeand the corresponding opening has a complementary shape.
 57. The torqueconverter of claim 51, wherein said openings are provided in areinforced portion of said torque transmitting member.
 58. The torqueconverter of claim 57, wherein said torque transmitting member includesa substantially disc-shaped body having a folded over radially outermostpart constituting said reinforced portion.
 59. The torque converter ofclaim 51, wherein said mass is an annular mass and said holding meansincludes forks each having prongs extending at least substantiallycircumferentially of said annular mass and engaging free end portions ofthe respective retaining members.
 60. The torque converter of claim 59,wherein the prongs of said forks are received in grooves providedtherefor in the free end portions of the respective retaining members.61. The torque converter of claim 60, wherein said forks are infrictional engagement with said torque transmitting member and with therespective retaining members.
 62. The torque converter of claim 51,wherein said holding means includes a discrete holding member for eachof said retaining members and a ring-shaped support for said holdingmembers, and further comprising means for securing said ring-shapedsupport to said torque transmitting member against accidental separationtherefrom.
 63. The torque converter of claim 51, wherein said means forholding comprises a ring having a plurality of circumferentiallyextending forks each engaging one of said retaining members and beingseparable from the respective retaining member in response to rotationof at least one of said ring and said mass relative to the otherthereof.
 64. The torque converter of claim 63, wherein said forkscooperate with said retaining members to hold said ring against movementrelative to said mass in the direction of said axis.
 65. The torqueconverter of claim 51, wherein said holding means includes a ring andfurther comprising means for preventing rotation of said ring and saidmass relative to each other when said retaining members are held in therespective openings.
 66. The torque converter of claim 65, wherein saidrotation preventing means includes at least one snap fastener.
 67. Thetorque converter of claim 66, wherein said snap fastener includes adetent provided on one of said ring and said torque transmitting memberand an opening for said detent in the other of said ring and said torquetransmitting member.